The present invention relates to the field of firefighting, and in particular to extinguishing forest, bush, field, brush or chemical fires with an emitted energy beam.
For a fire to ignite and be sustained four elements need to be present, the elements classified in the “Fire Tetrahedron” as: heat, fuel, an oxidizing agent (usually oxygen) and a chemical reaction. Removing one of the four elements is sufficient to suppress a fire. Typical methods of extinguishing tree based fires are: spraying the fire with water, or other fire suppressing chemical; and removing fuel such as trees and foliage from the vicinity of the fire.
Water is very effective in extinguishing fire as it removes both the heat from the fire, as the water vapor absorbs heat, and the oxidizing agent, as the water vapor displaces the oxygen in the vicinity of the fire. Any of a plurality of chemicals are in use for fire extinguishing, the chemicals either: breaking up the chemical reaction in the fire, such as in the case of Halon; cooling the fire; or removing the oxygen from the fire. In some cases chemicals are sprayed on the area surrounding the fire, creating a firebreak, thereby slowing down the advancement of the fire and allowing more time for direct extinguishing of the fire.
Disadvantageously, large amounts of water and/or chemicals may be needed in the case of a forest fire. In many cases the water and chemicals need to be brought from a distance and over uncomfortable terrain, the large amounts needed making this a difficult and time consuming task, whereas time is of the essence in fire fighting. Furthermore, a large amount of people and vehicles may be needed for the task, adding a large expense. Additionally, there may be a limit to how much water and/or chemicals can be brought to a fire, especially in the case of inaccessible terrain, where aerial fire fighting is required.
Removing the surrounding grass, trees and foliage from the vicinity of the fire is effective as the fire reaches an area without any fuel, called a firebreak, and therefore extinguishes. However, removing the surrounding fuel can be time consuming and because of the unpredictable properties of the weather can end up being useless as the fire has reached the area before all the fuel has been removed, or has changed direction to a different area. Furthermore, removing surrounding trees and foliage adds a large expense.
Japanese Showa Patent Publication 61-113470 published in 1986 is addressed to a fire extinguishing method that utilizes an emitted energy beam which is directed at the combustible particles in a fire. In particular, an emitted energy beam is emitted towards combustible material comprising carbon causing the carbon electrons to move, thus making it impossible for the carbon atoms to combine with oxygen even in a high temperature environment. By doing so, the fire is obstructed from continuing and eventually dies out. Unfortunately, such a system does not appear to be functional, and is not found in the field.
Similarly Patent Abstracts of Japan Publication 2006-015130 is addressed to the use of a pulsed laser to extinguish a fire by providing a blast wave which breakdowns the fire. The blast wave is produced by ablating either air or material at some distance from the fire. Unfortunately, such a system does not appear to be functional, and is not found in the field.
An article by Michael D. Waterworth, presented at the Symposium on Wildland Fire 2000, in April 1987 suggested the use of a recently developed laser ignition device for controlled burning of forest logging slash. Such a device has not been adapted for active fire fighting.